1. Field of Use
This invention relates generally to alternator driven capacitor discharge ignition systems for internal combustion engines. In particular it relates to an electronic ignition timing and detonation controller for use with such ignition systems to improve engine efficiency by providing additional spark advance in response to engine speed and detonation levels.
2. Description of the Prior Art
As U.S. Pat. No. 3,937,200 (owned by assignee of the present application) shows, some engines, such as multi-cylinder outboard motors, employ alternator driven capacitor discharge ignition systems wherein the alternator includes charging coils for charging the capacitor and a trigger coil to control ignition timing, i.e., time of spark plug firing. In some such systems, the trigger coil produces electrical pulses whose frequency and magnitude (voltage level or bias) are both proportional to engine speed, increasing or decreasing therewith, and both signal characteristics are used for timing. Typically, advance or retard of firing timing to obtain improved engine performance at various engine speeds is accomplished by adjustably positioning the trigger coil by means of a mechanical linkage in response to the position or movement of the engine throttle lever which controls engine speed. For example, with the throttle lever in engine-start position, the trigger coil is in retard position so that spark plug firing occurs after a piston reaches top dead center (TDC). Similarly, when the throttle lever is moved to increase engine speed, the trigger coil is moved to an advance position so that spark plug firing occurs before a piston reaches top dead center (TDC),